eNewsletter bug with Outlook and Apple Mail

Hello, i've found a bug in eNewsletter with Outlook and Apple mail. This is a very strange bug and i've never heard of it before.

It's about this piece of code in template.html

<div data-builder="email_content"> {EMAIL_BODY}
</div>

If i decrease the tabs of the code above, Outlook and Apple mail aren't able to recognize any images added to the content. I've tested this multiple times and im pretty sure of it.

Is there any explanation for this that you know about?

I'd like to hear from you.

Jordy